(a) Field of the Invention
The present invention relates to a system and method for estimating temperature of a rotor of a motor, and particularly, to a system and method for estimating temperature of a rotor of a motor to calculate temperature variation of the rotor using a measured data-based thermal model (e.g., thermal impedance model) and an energy loss model to then estimate temperature of the rotor with the temperature variation of the calculated temperature variation of the rotor.
(b) Description of the Related Art
Generally, it is well-known that a motor consists of a stator and a rotor. The stator refers to a fixed portion in the motor, including an iron core that supports a current-flowing coil and a frame to which the iron core is attached. The rotor is a rotatable portion in the motor, including a permanent magnet and an iron core. FIG. 1 is an exemplary drawing illustrating a schematic structure of a driving motor used in an environmentally-friendly vehicle, in which an air gap is formed between the stator 20 and rotor 10, a housing 40 is installed extraneous to the stator 20 to form a cooling channel 42, and oil or coolant flows in the cooling channel 42 to cool a motor 1.
Similar to a general motor, the rotor 10 includes permanent magnets 12 and an iron core 14, and the stator 20 includes an iron core 22 and a coil 24. The motor 1 of the environmentally-friendly vehicle may have different output and control performances as characteristics of the permanent magnets 12 embedded within the rotor 10 are varied. In general, magnetic flux of the permanent magnet 12 decreases as temperature increases, thereby resulting in a decreased output. Thus, to maintain equal torque (e.g., equal output), compensation control is required as temperature of the rotor varies.
However, the permanent magnets 12 are positioned inside of the rotor 10, causing difficult in attaching a temperature sensor configured to detect the permanent magnets 12, and a method for estimating the temperature of the rotor needs to be developed. Meanwhile, a method is known in which a temperature sensor is attached to a stator coil to detect temperature of a stator and the detected temperature of the stator is used to estimate temperature of a motor. However, this known method does not teach estimating temperature of the rotor and thus may not provide appropriate temperature compensation control according to temperature variation of the rotor.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.